WASHINGTON (AP) -- U.S. health regulators are barring imported drugs from a factory operated by Ranbaxy Laboratories, India's largest drugmaker, due to manufacturing and quality control problems.

The Food and Drug Administration's ban effectively stops the company from shipping drugs and drug ingredients from its Toansa plant in the Punjab province. A recent FDA inspection uncovered factory workers retesting drug ingredients that had failed quality testing to try and return positive results. Such practices are a violation of manufacturing standards for drugmakers that do business in the U.S.

In September the FDA placed a similar hold on imports from Ranbaxy's Mohali facility. Both actions were taken under a 2012 legal settlement with the FDA, which subjects Ranbaxy to extra scrutiny and inspections to improve its drug production.